[Introduction] It has been reported that endometrial function is regulated through interactions between endometrial epithelial cells (EEC) and endometrial stromal cells (ESC). The present study was undertaken to study stromal-epithelial interaction for successful implantation.[Methods]EEC and ESC were isolated by the sequential enzymatic dissociation and differential sedimentation. Isolated EEC were cultured on Matrigel (basement membrane extract)-coated tissue culture inserts, and ESC were cultured on the bottom of tissue culture well. After cell attachment, the inserts with EEC were transferred to the tissue culture wells containing ESC in order to allow both cells to interact, and they were incubated with estradiol (E, 10^<-8> M) and/or medroxyprogesterone acetate (MPA, 10^<-6>M). As controls, EEC on the insert or ESC in the tissue culture well were incubated. After treatments, Leukemia inhibitory factor (LIF) expression in EEC, which is essential for successful implantation, was an
… Morealyzed. In ESC, morphological changes and insulin-like growth factor-binding protein-1 (IGFBP-1), which is a specific marker for decidualization, were analyzed.[Results] 1. In the absence of ESC, neither E or MPA (3 days culture) had significant effect on LIF mRNA expression in EEC. However, in the presence of ESC, E significantly stimulated LIF mRNA expression in EEC, but MPA had no effect. LIF mRNA expression in ESC was negligible. E-induced LIF expression in EEC was mediated by insulin-Like growth factor-I (IGF-I) secreted by ESC in response to E. 2. By the treatment with E+MPA for 12 days, IGFBP-1 mRNA expression in ESC was significantly increased, accompanied with morphological changes. However, in the presence of EEC, these changes accompanied with decidualization in response to E+MPA were inhibited. Inhibition of decidualization may be favorable for implantation.[Conclusions] The present study suggests the significance of stromal-epithelial interaction for successful implantation. Less